The present invention relates to water dispersible forms of alkyl bis-amides of fatty acids (sometimes referred to herein simply as "bis-amides") and the methods of making same. Bis-amides enjoy a wide variety of use. For example, they may be useful an antiblocking agents in adhesives; for powder metallurgy; for lubricating polymer beads (as a flow lubricant); additive for the dispersion of pigments. In addition bis-amides may be useful metal lubricants, e.g. in metal drawing and rolling. These are but a few of the many uses which have been made of bis-amides. In most instances, bis-amides, which are waxes, desirably should be formulated in an aqueous suspension so as to provide a uniform dispersion which upon dilution, if necessary by the user, will provide a uniform coating. The use of aqueous bis-amide dispersions has clear advantages over solvent systems because of the absence of fumes and flammability hazards.
One of the problems attendant to the use of such bis-amides as ethylene bis-stearamide (EBS) arises from the difficulty one commonly experiences in trying to disperse the bis-amides in water. The problem is attributable to the hydrophobic nature, and high melting point (140.degree. to 147.degree. C. for EBS) of the bis-amides. Nevertheless, there is a need for aqueous bis-amide dispersions on an ongoing commercial basis.
One established procedure for dispersing bis-amides is to slowly add the bis-amide in a finely ground state to a hot water solution containing dispersants. Generally, the resulting dispersions have a relatively short life and poor shelf-stability due to the tendency of the bis-amide to settle out of suspension, particularly when diluted. Once separated, the bis-amides are difficult to redisperse. These problems are aggravated by the time required for the finished dispersion to reach its user as well as normal storage. Furthermore, such dispersions, because of their high water content, are costly to transport, and unless properly protected will freeze in cold weather. Alternatively, preparation of satisfactory dispersions using the dry ingredients is generally a difficult and time consuming procedure owning primarily to a lack of proper equipment and know-how on the part of the user.
For these reasons, bis-amide dispersions cannot be prepared by simply heating the wax together with water, or even by melting the wax and adding the melt to the water.
To prepare good, pourable dispersions of bis-amides, it is first necessary to use an effective dispersant, and second, to somehow circumvent the high melting point problem.
Clearly, there is a need for an improved dispersion of bis-amide waxes, in either hot or cold water.
Accordingly, it is the primary object of the present invention to provide bis-amide wax compositions which may be easily and readily dispersed in water.
It is a further object of the present invention to provide dry bis-amide waxes which when mixed with water will form a stable long lasting dispersion.
Still another object of the present invention is to provide a useful method of preparing readily dispersible bis-amide compositions.
These and other objects of the present invention will become more apparent from the discussion which follows.